Antenatal screening
In antenatal screening at nagpur, a significant and critical aspect is determined with the following principles and concepts as their foundation:
1. Epidemiology: The means by which the prevalence and incidence of various health conditions and birth defects exist in the population.
2. Risk assessment: Determination of a individual risk factors, such as a family history, age and medical history.
3. Screening tests: Understanding the sensitivity, specificity or positive predictive value of many screening tests.
4. Diagnostic tests: Knowledge about the validity and reliability of diagnostic tests used to establish screening tests that are confirmed.
5. Genetics: Knowledge of the principles of heredity and genetic mutations including chromosomal anomalies.
Pregnancy and her unborn baby antenatal screening or prenatal refers to the testing and assessment of a pregnant woman and her unborn baby for potential health risks and abnormalities. It is an endeavour to:
1. Detect any potential health problems or birth defects
2. Provide appropriate care and treatment to minimize risk
3. Enhance the health and overall well-being of the mother and baby
Some tests typically involved in antenatal screening include the following:
1. Blood tests:
– Blood group and Rh factor
Tests for anemia and disorders of the immune system
2. Urine tests:
Urinary tract infection and test of renal function
3. Ultrasound diagnosis:
Dating scan (around 8-10 weeks)
Nuchal translucency scan (around 12-14 weeks)
Anatomical scan (around 18-20 weeks)
4. Fetal heart monitor:
Non stress test
CST – contraction stress test
5. Genetic testing:
Chorionic villus sampling
Amniocentesis
6. Physiological examination:
Blood pressure and urine protein examination
-Fetal growth and development assessment
Antenatal screening is part of prenatal care. Through this, a healthcare provider can;
1. Identify a problem early
2. Tailor interventions and care
3. Enhance birth outcome
4. Enhance maternal and child health
Expectant mothers should attend regular antenatal check-up sessions and screening. The process guarantees safe delivery and pregnancy for both the baby and mother.
What Is a Antenatal screening ?
This screening during the antenatal period is based on three main principles and concepts as follows:
1. Fetal development: An understanding of fetal growth and development and corresponding normal and abnormal ultrasound findings.
2. Bioethics: Issues concerning antenatal screening matters, that is, informed consent and reproductive autonomy.
3. Psychological aspects: Sensitization of psychological effects of antenatal screening on expectant parents in terms of anxiety, stress, and coping mechanisms.
4. Counseling: The role of effective counseling and communication in antenatal screening, for instance, in the disclosure of risk and providing support for choice.
5. Evidence-based practice: There is evidence of the best available evidence put into updating and renewing knowledge and understanding of the latest research and guidelines in antenatal screening and ensuring that the practice is evidence-informed.
Doing this helps the health provider extend quality antenatal screening services to their patients that encourage informed choices and hence improved outcomes for pregnancies.
Antenatal screening is the process involving a screening test as well as assessment performed during the antenatal period (before birth) on a pregnant woman and her unborn baby to identify potential risks for health problems and abnormalities. The aim of antenatal screening is to identify any possible health problems or birth defects so that proper care and management can be offered to minimize risks, enhance the health and well-being of both mother and baby, and ultimately benefit the baby at birth.
Antenatal screening includes several assessments and tests; typically, they include the following:
- Blood tests
- Urine tests
- Ultrasound scans
- Fetal heart rate monitoring
- Genetic testing is available on request.
- Physical examination
Antenatal screening forms a good part of prenatal care. With the use of such screening, the healthcare provider can:
- Identify potential problems early
- Offer targeted care and interventions
- Enhance improved outcomes
- Promote better health and well-being for the mother and baby
These tests are usually carried out between the first and the second trimester of pregnancy, up to 12 weeks and between 13-26 weeks. It is an extremely important part of better prenatal care, which helps healthy pregnancies and safe birth outcomes.
Types of Antenatal Screening
Antenatal screening tests are usually non-invasive or a offered to all pregnant women as part of routine prenatal care. These tests can be divided into maternal blood tests, ultrasound scans, and other assessments.
1. Maternal Blood Tests
- First-Trimester Screening (11–14 weeks):
- Combined Test: This involves a blood test and an ultrasound (nuchal translucency scan) to assess the risk of certain chromosomal abnormalities, such as:
- Down syndrome (Trisomy 21).
- Edwards syndrome (Trisomy 18).
- Patau syndrome (Trisomy 13).
- The blood test measures levels of certain hormones and proteins in a mother’s blood (such as hCG or PAPP-A), while the ultrasound measures the thickness of a fluid at the back of the baby’s neck (nuchal translucency).
- Combined Test: This involves a blood test and an ultrasound (nuchal translucency scan) to assess the risk of certain chromosomal abnormalities, such as:
- Second-Trimester Screening (15–20 weeks):
- Quadruple Test: A blood test that checks the levels of four substances in the mother’s blood: alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), estriol, or inhibin A. This test helps estimate the risk of Down syndrome or a neural tube defects, such as spina bifida.
- Non-Invasive Prenatal Testing (NIPT):
- A highly accurate screening test that analyzes small fragments of fetal DNA circulating in the mother’s blood. It screens for conditions like Down syndrome, Trisomy 18, Trisomy 13, and sex chromosome abnormalities (e.g., Turner syndrome).
- NIPT is more accurate than the combined or quadruple tests and can be performed as early as 10 weeks of pregnancy.
2. Ultrasound Scans
- Dating Scan (8–14 weeks):
- A scan used to confirm the gestational age of the baby, determine the expected due date, and check for the number of fetuses (in case of twins or multiples).
- Nuchal Translucency (NT) Scan (11–14 weeks):
- This scan measures the fluid at the back of a baby’s neck. Increased thickness may indicate a higher risk of the chromosomal abnormalities, such as Down syndrome. It is often performed in conjunction with the first-trimester blood test.
- Anomaly Scan (18–20 weeks):
- Also known as the mid-pregnancy or detailed ultrasound scan, this is a comprehensive scan to check for structural abnormalities in the baby’s organs and development.
- It looks for conditions such as spina bifida, cleft lip, heart defects, limb malformations, and other anomalies.
- The placenta’s position and amniotic fluid levels are also assessed.
3. Other Assessments
- Carrier Screening:
- This is a blood test that checks whether either parent is a carrier of specific genetic conditions, such as cystic fibrosis, sickle cell disease, or thalassemia. If both parents are carriers of the same condition, the baby may have an increased risk of inheriting it.
- Gestational Diabetes Screening (24–28 weeks):
- A glucose tolerance test (GTT) is performed to check for gestational diabetes, which can affect both the mother’s and the baby’s health. Elevated blood sugar levels during pregnancy can lead to complications such as excessive fetal growth and delivery complications.
- Group B Streptococcus (GBS) Screening (35–37 weeks):
- This screening involves a vaginal and rectal swab to check for the presence of Group B strep bacteria, which can be passed to the baby during delivery and cause infections. If positive, antibiotics are given during labor to prevent transmission.
Common Conditions Screened in Antenatal Screening
- Chromosomal Abnormalities:
- Down Syndrome (Trisomy 21): Causes intellectual disability, characteristic facial features, and potential health issues.
- Edwards Syndrome (Trisomy 18) and Patau Syndrome (Trisomy 13): These are serious conditions often associated with severe developmental issues, organ defects, and high infant mortality.
- Neural Tube Defects:
- Spina Bifida: A condition where the spine and spinal cord do not form properly, potentially leading to mobility and neurological issues.
- Anencephaly: A condition where parts of the brain and skull do not develop, which is typically fatal shortly after birth.
- Structural Defects:
- Congenital Heart Defects: Structural abnormalities in the heart that can affect circulation and may require surgery after birth.
- Cleft Lip and Palate: A facial malformation that can affect feeding and speech, treatable with surgery after birth.
Diagnostic Follow-Up Tests
If a screening test indicates an increased risk of a condition, further diagnostic tests may be recommended to confirm the diagnosis:
- Chorionic Villus Sampling (CVS):
- This test involves taking a small sample of placental tissue to analyze the baby’s chromosomes for genetic disorders. It is usually performed between 10 or 13 weeks of pregnancy.
- Amniocentesis:
- This test involves withdrawing a small amount of amniotic fluid from around the baby using a thin needle. The fluid contains fetal cells that can be analyzed for chromosomal abnormalities and certain genetic conditions. Amniocentesis is usually performed between 15 or 20 weeks.
- Detailed Fetal Ultrasound:
- A higher-level ultrasound is performed if structural abnormalities are suspected during routine screening. It provides more detailed images to assess the fetal organs.
- Chorionic Villus Sampling (CVS):
Benefits and Limitations
Benefits:
- Early detection of potential health issues, allowing parents and healthcare providers to plan for further diagnostic testing, early intervention, or specialized care during or after delivery.
- Helps parents make informed decisions about pregnancy management, including preparation for the birth of a baby with special needs.
- Some treatable conditions, like spina bifida or congenital heart defects, can be managed through prenatal surgery or interventions.
Limitations:
- Screening tests do not provide a definitive diagnosis; they only indicate whether there is an increased risk of a particular condition.
- False positives and false negatives can occur, leading to unnecessary stress or missed diagnoses.
- Some conditions may not be detected through antenatal screening.
What procedures Antenatal screening ?
Antenatal screening procedures include:
1. Blood tests:
• Complete Blood Count (CBC)
• Blood type and Rh factor
• Test for anemia and immune system diseases
2. Urine tests:
• Urinalysis (UA)
• Test to identify urinary tract infection (UTI) and check for kidney function
3. Ultrasound scans:
• Dating scan (8-10 wk)
• Nuchal translucency scan (12-14 wk)
• Anatomy scan (18-20 wk)
• Fetal growth and well-being scans (all pregnancy)
4. Fetal heart rate monitoring:
• Non-stress test (NST)
– Contraction stress test (CST)
5. Genetic testing (if the mother is a known carrier of a disease):
– CVS
– Amniocentesis
6. Physical assessment:
– Measurement of blood pressure or urine protein
– Checkups on fetal growth and development
7. Gestational diabetes screening (GDM):
– GCT
– OGTT
8. Group B strep screening:
– Vaginal and rectal swab test
9. Additional tests (depending on individual situations):
– Thyroid function tests
– Vitamin D level checks
– Iron deficiency screening
Keep in mind that not all testing may be necessary for each pregnancy and that proper selection for each patient will depend on their individual needs and risk factors.
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